Electronic Control Module (ECM)

ECM controls engine operation based on input signals from various sensors. ECM also controls transmission. If self-diagnostic system detects a fault, it stores a trouble code in the ECM memory, and turns on the Malfunction Indicator Light (MIL), also known as CHECK ENGINE light. For information, see TESTS W/CODES - OBD-II article.

If the ECM detects a system fault, it controls fuel injection and ignition timing at predetermined levels as a back-up (fail-safe) function to make it possible to continue vehicle operation. If engine speed exceeds 6500 RPM, ECM stops fuel injection until engine speed decreases to less than 6500 RPM. This prevents engine overrun.